An orange-yellow-emitting Lu2−xMg2Al2−yGaySi2O12:xCe3+ phosphor-in-glass film for laser-driven white light

Abstract

Phosphor-converted white laser diode (pc-wLD) technology requires high-color-quality white light, which involves the development of an efficient red-emitting phosphor color converter. With regard to this, we have developed a new kind of orange-yellow-emitting Lu_2−xMg₂Al_2−yGa_ySi₂O₁₂:xCe³⁺ (LMAGS:Ce³⁺) solid-solution phosphor, which shows the desired abundant red-emissive components and nanosecond-range luminescent decay. LMAGS:Ce³⁺ is further compounded into an all-inorganic phosphor-in-glass (PiG) composite tightly bonded to a high-thermal-conductivity sapphire plate (SP) in the form of a film. There is no obvious interfacial reaction between phosphor and glass during co-sintering, which ensures good luminescent properties are retained. A comparative study was conducted to reveal the microstructure–property relationship and the key influencing factors of luminescence saturation upon being driven by a blue laser. “One-dimensional photonic crystal film” and “phosphor wheel” designs were adopted to further enhance the luminescent performance, successfully improving the luminous flux of the generated white light to 393.8 lm @ 5 W mm⁻² under static–transmissive excitation mode and 1080 lm @ 20 W mm⁻² under rotatory–reflective excitation mode. Probing into the luminescence saturation mechanism, the effects of thermal saturation and optical saturation were demonstrated, accounting for 44.0% and 56.0% contributions, respectively. A fabricated prototype neutral/warm-white LD lighting source based on LMAGS:Ce³⁺ PiG film-on-SP shows high light collimation and comfortable visual perception, demonstrating the bright application potentials of the developed composite material.